---
id: 655a493ab909a96f7c316cd5
title: ステップ 36
challengeType: 20
dashedName: step-36
---

# --description--

Below the `if` statement, add an `elif` clause to check if the right child of the current node (`node.right`) is `None`.

If the previous condition is met, it means there is no right child. So, return the left child of the current node from the `elif` block as a replacement.

# --hints--

You should create an `elif` statement that checks if the right child of the current node is `None`.

```js
assert.match(code, /elif\s+node\.right\s+is\s+None/);
```

You should return the left child of the current node.

```js
assert.match(code, /return\s+node\.left/);
```

# --seed--

## --seed-contents--

```py
class TreeNode:
    def __init__(self, key):
        self.key = key
        self.left = None
        self.right = None

class BinarySearchTree:
    def __init__(self):
        self.root = None

    def insert(self,key):
        self.root = self._insert(self.root, key)

    def _insert(self, node, key):
        if node is None:
            return TreeNode(key)
        if key < node.key:
            node.left = self._insert(node.left, key)
        elif key > node.key:
            node.right = self._insert(node.right, key)
        return node

    def search(self, key):
        return self._search(self.root, key)

    def _search(self, node, key):
        if node is None or node.key == key:
            return node
        if key < node.key:
            return self._search(node.left, key)
        return self._search(node.right, key)

    def delete(self, key):
        self.root = self._delete(self.root, key)

    def _delete(self, node, key):
        if node is None:
            return node
        if key < node.key:
            node.left = self._delete(node.left, key)
        elif key > node.key:
            node.right = self._delete(node.right, key)
--fcc-editable-region--
        else:
            if node.left is None:
                return node.right
--fcc-editable-region--
```
